Quantum cryptography, which relies on the laws of physics to ensure that encoded messages can be deciphered only by those authorized to do so, has for years promised to deliver encryption far stronger than the public key infrastructures (PKI) more commonly used today. Trouble is, there are few, if any, documented uses of this quantum technology outside of lab settings.

But this is about to change: On Sunday during Switzerland's national elections officials in Geneva will use quantum cryptography to secure the network linking their ballot data entry center to the government repository where votes are stored. Quantum cryptography relies on a highly secure exchange of the keys used to encrypt and decrypt data between a sender and a receiver, and Swiss election officials' confidence that this technology is ready for prime time will provide a strong tailwind for a technology still in its adolescence.

"This occasion marks quantum technology's real-world debut," says University of Geneva professor Nicolas Gisin. "This is the first time this is being done for a real customer who's using real data."

Indeed, researchers at the university, along with id Quantique, SA, a quantum encryption technology provider spun off by the school, are hoping the elections will provide much-needed momentum for their pilot quantum communications network called the SwissQuantum project. Headed by Gisin, with support from the Swiss National Science Foundation's National Center of Competence in Quantum Photonics Research, SwissQuantum is expected to provide an additional outlet for working out the kinks that have prevented wider use of quantum encryption technology.

Although Swiss citizens will vote using a paper ballot, information about the number of votes will be keyed into computers after the polls close. That is where the 100,000 euro ($140,000) id Quantique encryption system kicks in, scrambling the data at the blazing-fast speed of one gigabit per second and sending it from those computers to a data center run by the university's center for information technology.

With quantum encryption, the sender encodes the encryption key on an individual quantum particle, such as a photon or electron, and sends that particle via a fiber-optic line to its destination. Information about key characteristics of the particle—such as its size or level of polarization—is sent to the destination as well. If the particle that arrives is distorted in any way, it is discarded and another key is sent. This protects quantum encryption and quantum key distribution from third-party eavesdropping because a particle cannot be intercepted without changing its quantum state.

"Quantum key distribution is used as a novel method to exchange between two people a key that is then used to encrypt a message," says Jonathan Habif, a research scientist with BBN Technologies in Cambridge, Mass., a company that in 2003 worked with the Defense Advanced Research Projects Agency (DARPA) to create the world's first quantum key distribution network. "You're not transmitting a message, but rather an encryption key. The beauty of quantum key distribution is it gives you a method to exchange keys with a security method that is rooted in the laws of physics."

Quantum encryption's chief impediment has been its inability to send information great distances. Scientists at the U.S. Department of Commerce's National Institute of Standards and Technology (NIST), the U.S. Department of Energy's Los Alamos National Laboratory and Albion College in Michigan generated and transmitted secret quantum keys over 185 kilometers (115 miles) of fiber-optic cable during an experiment last year—the farthest such information has traveled. The first experimental quantum encryption prototype, created in 1991, was able to send information a mere 32 centimeters (12.6 inches).

Quantum cryptography, which relies on the laws of physics to ensure that encoded messages can be deciphered only by those authorized to do so, has for years promised to deliver encryption far stronger than the public key infrastructures (PKI) more commonly used today. Trouble is, there are few, if any, documented uses of this quantum technology outside of lab settings.

But this is about to change: On Sunday during Switzerland's national elections officials in Geneva will use quantum cryptography to secure the network linking their ballot data entry center to the government repository where votes are stored. Quantum cryptography relies on a highly secure exchange of the keys used to encrypt and decrypt data between a sender and a receiver, and Swiss election officials' confidence that this technology is ready for prime time will provide a strong tailwind for a technology still in its adolescence.

"This occasion marks quantum technology's real-world debut," says University of Geneva professor Nicolas Gisin. "This is the first time this is being done for a real customer who's using real data."

Indeed, researchers at the university, along with id Quantique, SA, a quantum encryption technology provider spun off by the school, are hoping the elections will provide much-needed momentum for their pilot quantum communications network called the SwissQuantum project. Headed by Gisin, with support from the Swiss National Science Foundation's National Center of Competence in Quantum Photonics Research, SwissQuantum is expected to provide an additional outlet for working out the kinks that have prevented wider use of quantum encryption technology.

Although Swiss citizens will vote using a paper ballot, information about the number of votes will be keyed into computers after the polls close. That is where the 100,000 euro ($140,000) id Quantique encryption system kicks in, scrambling the data at the blazing-fast speed of one gigabit per second and sending it from those computers to a data center run by the university's center for information technology.

With quantum encryption, the sender encodes the encryption key on an individual quantum particle, such as a photon or electron, and sends that particle via a fiber-optic line to its destination. Information about key characteristics of the particle—such as its size or level of polarization—is sent to the destination as well. If the particle that arrives is distorted in any way, it is discarded and another key is sent. This protects quantum encryption and quantum key distribution from third-party eavesdropping because a particle cannot be intercepted without changing its quantum state.

"Quantum key distribution is used as a novel method to exchange between two people a key that is then used to encrypt a message," says Jonathan Habif, a research scientist with BBN Technologies in Cambridge, Mass., a company that in 2003 worked with the Defense Advanced Research Projects Agency (DARPA) to create the world's first quantum key distribution network. "You're not transmitting a message, but rather an encryption key. The beauty of quantum key distribution is it gives you a method to exchange keys with a security method that is rooted in the laws of physics."

Quantum encryption's chief impediment has been its inability to send information great distances. Scientists at the U.S. Department of Commerce's National Institute of Standards and Technology (NIST), the U.S. Department of Energy's Los Alamos National Laboratory and Albion College in Michigan generated and transmitted secret quantum keys over 185 kilometers (115 miles) of fiber-optic cable during an experiment last year—the farthest such information has traveled. The first experimental quantum encryption prototype, created in 1991, was able to send information a mere 32 centimeters (12.6 inches).

The quantum encryption work being done in Switzerland will be an important learning experience, particularly because the technology is still in its early stages of development, Habif says. Quantum key distribution systems available today work only over short distances and require an exponential amount of computing and network resources as that distance grows. "If you give the field five to 10 years, you will see the beginnings of a scalable quantum key distribution system," he says, adding that a quantum signal cannot be amplified today because a repeater would destroy the photons and the data they carry as it inspects the photons. "You need a quantum repeater that will preserve the fidelity of the quantum information as it moves through the network." Of course, the presence of such a repeater could also weaken the sanctity of the encrypted transmission if the fiber-optic network is not properly secured.

Skeptics say that although the Swiss government's plan to demonstrate quantum cryptography is interesting, it is not likely to vastly improve the integrity of elections. "This makes no positive contribution to voting security or trustworthiness," says David Dill, a Stanford University professor of computer science and founder of the Verified Voting Foundation, a nonprofit organization pushing for the implementation of voting processes that can more easily be verified and audited. "The transmission of vote data to the central server is really one of the lesser issues. To the extent that that's a problem, it can be adequately solved at less cost and risk using conventional cryptography."

In order to have a voting system that allows for truly verifiable election results, information has to be protected from the time the vote is cast to the time it is counted and the election is certified, Dill says. So could the Swiss experience help iron out problems brought to light during the 2000 U.S. presidential election fiasco, which ended in a Supreme Court decision that ushered George W. Bush into the White House? Extremely unlikely, Dill says, noting that the U.S. still has no minimum standards for conducting federal elections that would create consistency across the country.

The quantum encryption work being done in Switzerland will be an important learning experience, particularly because the technology is still in its early stages of development, Habif says. Quantum key distribution systems available today work only over short distances and require an exponential amount of computing and network resources as that distance grows. "If you give the field five to 10 years, you will see the beginnings of a scalable quantum key distribution system," he says, adding that a quantum signal cannot be amplified today because a repeater would destroy the photons and the data they carry as it inspects the photons. "You need a quantum repeater that will preserve the fidelity of the quantum information as it moves through the network." Of course, the presence of such a repeater could also weaken the sanctity of the encrypted transmission if the fiber-optic network is not properly secured.

Skeptics say that although the Swiss government's plan to demonstrate quantum cryptography is interesting, it is not likely to vastly improve the integrity of elections. "This makes no positive contribution to voting security or trustworthiness," says David Dill, a Stanford University professor of computer science and founder of the Verified Voting Foundation, a nonprofit organization pushing for the implementation of voting processes that can more easily be verified and audited. "The transmission of vote data to the central server is really one of the lesser issues. To the extent that that's a problem, it can be adequately solved at less cost and risk using conventional cryptography."

In order to have a voting system that allows for truly verifiable election results, information has to be protected from the time the vote is cast to the time it is counted and the election is certified, Dill says. So could the Swiss experience help iron out problems brought to light during the 2000 U.S. presidential election fiasco, which ended in a Supreme Court decision that ushered George W. Bush into the White House? Extremely unlikely, Dill says, noting that the U.S. still has no minimum standards for conducting federal elections that would create consistency across the country.